WWI Prussian Insignia

WWI Prussian Insignia - Three Collar Disks (two are silvered copper, unmarked, 29.5 mm each, flat insert on their reverses; one is bronze, marked "EXTRA FEIN E.A.Q." on the reverse, 29.6 mm); and two Cuff Buttons (silvered bronze, one marked "EXTRA FEIN A & S" on the reverse, 24 mm, flat insert on the reverse; the other is marked "EXTRA FEIN", 25 mm, with a recessed flat insert on the reverse). Each have intact loops, light contact and wear, very fine.